Nematodes are active, flexible, elongate organisms that live on moist surfaces or in liquid environments, including films of water within soil and moist tissues within other organisms. Many species of nematodes have evolved to be very successful parasites of plants and animals and, as a result, are responsible for significant economic losses in agriculture and livestock.
Plant parasitic nematodes can infest all parts of the plant, including the roots, developing flower buds, leaves, and stems. Plant parasites can be classified on the basis of their feeding habits into a few broad categories: migratory ectoparasites, migratory endoparasites, and sedentary endoparasites. Sedentary endoparasites, which include root knot nematodes (Meloidogyne) and cyst nematodes (Globodera and Heterodera), can establish long-term infections within roots that may be very damaging to crops.
There is an urgent need in the industry for effective, economical, and environmentally safe methods of controlling nematodes. Continuing population growth, famines, and environmental degradation have heightened concern for the sustainability of agriculture.
Recently, a class of 3,5-disubstituted-1,2,4-oxadiazoles has been shown to exhibit potent, broad spectrum nematicidal activity. See generally U.S. Pat. No. 8,435,999 and U.S. Pat. No. 8,017,555, the contents of which are expressly incorporated herein by reference. The 3,5-disubstituted-1,2,4-oxadiazoles disclosed in U.S. Pat. No. 8,435,999 and U.S. Pat. No. 8,017,555 are generally characterized by low water solubility.
Two-phase suspension concentrates, which comprise solid particles of a compound suspended in an aqueous medium, are generally known in the art. In the context of seed treatment applications, suspension concentrates are known to offer several potential advantages, including high active loading, ease of handling, and reduced toxicity and flammability associated with solvents. The suspension concentrate compositions known in the art, however, are also prone to instability and settling upon storage, and may not provide a uniform distribution of the active nematicide compound in a manner that enhances bioavailability.
To be effective for use as a seed treatment composition, a nematicidal suspension concentrate desirably satisfies several key requirements. The nematicidal active ingredient must be effectively incorporated into a suspension having commercially acceptable storage stability. The suspension should exhibit acceptable storage stability over a wide temperature range and even where the nematicidal active ingredient is present in a high loading, which reduces the required volume of the composition and, therefore, reduces the expense of storage and shipping. The nematicidal active ingredient must also be amenable to transfer from the suspension concentrate to the surface of the seed, such that the desired loading can be efficiently achieved. Moreover, following application to the seed, it may be desirable for the nematicidal active ingredient to effectively migrate from the seed surface to the root zone of the surrounding soil.
Accordingly, there remains a need in the art to develop compositions that enable the efficient use of the above-mentioned potent and effective 3,5-disubstituted-1,2,4-oxadiazole nematicidal compounds in large-scale, commercial agricultural applications, particularly in seed treatment applications, to protect against nematode infestations.